Assembly method of a photovoltaic panel of the back-contact type with pre-fixing of the cells, and combined loading and pre-fixing station

Abstract

Automatic assembly method of a photovoltaic panel with cells of the back-contact type provided with a conductive backsheet with a thermoplastic encapsulating layer; the loading of the cells occurs in combination with their pre-fixing in a combined station sequentially placed before the superimposition of the upper encapsulating layer and after the laying of the conductive adhesive. The loading is carried out with a first device of the automatic mechanical hand type which takes a group of cells, aligns them with the back contacts in correspondence of the holes and lays them vertically from above. Furthermore, a second device of the presser-heater type carries out the pre-fixing of the cells holding them in the final position also with localized heating on at least one portion of each cell in such a way as to activate the adhesive function of the underlying thermoplastic encapsulating layer. A combined loading and pre-fixing station is also disclosed.

The invention claimed is: 
     
       1. A method for assembling a photovoltaic panel with back-contact cells of crystalline silicon, the method comprising:
 horizontally positioning a conductive back sheet with an encapsulating layer having holes facing upwardly; 
 laying a conductive material in the holes; 
 loading the back-contact cells such that a sensitive face of the back-contact cells faces upwardly so as to form a front side of the photovoltaic panel and such that contact of the back-contact cells is toward a back side of the photovoltaic panel; 
 superimposing an upper encapsulating layer on the photovoltaic panel; 
 laying a front glass onto the upper encapsulating layer; 
 turning the photovoltaic panel over; and 
 moving the turned-over photovoltaic panel to a rolling furnace for a final rolling, the steps of loading and a fixing of the back-contact cells occurring simultaneously with each other in a coordinated manner, the steps of loading and fixing being carried out in a combined station which is sequentially placed before the step of superimposing and after the step of laying of the front glass. 
 
     
     
       2. The method of  claim 1 , wherein the loading of the back-contact cells is carried out by a first device which has an automatic mechanical hand, wherein the first device takes the cells and aligns them with the back contacts in correspondence to the holes and lays them vertically from above onto the encapsulating layer, wherein a second device with a presser-heater carries out the pre-fixing of the back-contact cells by holding them and performing localized heating on at least one portion of each back-contact cell so as to activate an adhesive function of the encapsulating layer, wherein said second device holds each back-contact cell in a correct position until the end of the step of prefixing, wherein said second device performs the localized heating downwards with a heater on at least one portion of each back-contact cell in correspondence to at least one rectilinear edge of the back-contact cell and without compromising the back contacts, wherein a pressure of the presser-heater and a heater of the presser-heater are integrated in the same multifunction head which is in said second device, wherein said first device and said second device are coordinated with each other to operate on the same back-contact cells in an alternate sequential manner, the step of prefixing being carried out by said second device after said first device has completed the step of loading. 
     
     
       3. The method of  claim 2 , wherein said first device loads one row of the back-contact cells at a time, wherein said second device carries out the step of prefixing simultaneously on all the back-contact cells of two adjacent rows while placing itself parallel and symmetrically midway between the two adjacent two rows, the step of prefixing being carried out while said first device prepares the loading of a following row, said second device comprising a supporting element which has a plurality of the multifunction heads, each of the plurality of multifunction heads acting on an adjacent pair of back-contact cells belonging to the two adjacent rows along closest respective parallel edges thereof such that with a head and a heater of the multifunction head simultaneously carries out the step of prefixing two portions of adjacent back-contact cells included in a common heated area, wherein the step of prefixing occurs in correspondence to a superimposed portion of the heated area which is superimposed in a symmetrical manner on the rectilinear edges closest to each other of a pair of adjacent back-contact cells, a width of the heated areas is equal to or less than a length of the rectilinear portion of the edge of the back-contact cell, the superimposed portion is equal to or less than 80% of a distance between the edge and a center of the back contact. 
     
     
       4. The method of  claim 3 , wherein the localized heating is started within 10 seconds from the step of laying of the back-contact cell in its final position, wherein the localized heating lasts between 0.5 seconds and 10 seconds.